This invention relates generally to semiconductors, and more specifically to methods and apparatus for making anisotropic electrical interconnects.
Anisotropic electrical interconnects are known in the art. U.S. Pat. No. 6,194,492 B1 discloses an anisotropic conductive film which exhibits a conductivity in the thickness direction thereof by pressurizing the film in the thickness direction, the film including: an adhesive; and conductive particles dispersed in the adhesive; wherein the adhesive is a thermosetting or photosetting adhesive containing as a main component at least one kind selected from a group consisting of (a) a polymer obtained by acetalation of a polyvinyl alcohol, (b) a compound containing an allyl group, (c) a monomer containing an acryloxy group or methacryloxy group, and (d) a polymer obtained by polymerization of one or more selected from a group consisting of an acrylic monomer and a methacrylic monomer.
U.S. Pat. No. 5,932,339 discloses an anisotropically electricity-conductive film obtainable by dispersing in an adhesive agent electrically conductive particles, the adhesive agent being a curable adhesive agent comprising as a major component at least one polymer selected from the group consisting of an ethylene-vinyl acetate copolymer; a copolymer of ethylene, vinyl acetate and an acrylate and/or methacrylate monomer; a copolymer of ethylene, vinyl acetate and maleic acid and/or maleic anhydride; a copolymer of ethylene, an acrylate and/or methacrylate monomer and maleic acid and/or maleic anhydride; and an ionomer resin wherein molecules of an ethylene-methacrylic acid copolymer are linked with each other through a metal ion.
U.S. Pat. No. 5,865,703 discloses an anisotropic, electrically conductive adhesive film including insulating adhesive, electrically conductive particles dispersed in the electrically insulating adhesive, and transparent, spherical glass particles dispersed in the insulating adhesive.
U.S. Pat. No. 5,162,087 discloses an anisotropic conductive adhesive composition comprising an insulating adhesive component and particles dispersed in said insulating adhesive component, said anisotropic conductive adhesive composition being characterized in that said insulating adhesive component comprises a copolymer of acrylic ester having an alkyl group of 1-4 carbon atoms and a maleimide derivative, 5 to 60 parts by weight, based on 100 parts by weight of the copolymer, of a thermosetting resin, and 0.05 to 5.0 parts by weight, based on 100 parts by weight of the copolymer, of a coupling agent, and said particles are metallic-layer containing particles comprising a core made of resin, a metallic layer covering said core and a resin layer formed from finely divided resin fixed by the dry blending method on the surface of said metallic layer.
U.S. Pat. No. 4,740,657 discloses an adhesive composition or film capable of exhibiting anisotropic-electroconductivity comprising electroconductive particles comprising polymeric core materials coated with thin metal layers, and electrically insulating adhesive component.
U.S. Pat. No. 5,965,064 discloses an anisotropically electroconductive adhesive to be used for establishing electric connection between terminals of, for example, an IC chip and of a circuit pattern, which adhesive comprises an electrically insulating adhesive matrix and electroconductive particles comprise at least two electroconductive particulate products of different average particle sizes and wherein each particle of both the particulate products is coated with an electrically insulating resin insoluble in the insulating adhesive matrix.
U.S. Pat. No. 5,302,456 discloses an anisotropic conductive material including microcapsules dispersed in a bonding resin. The micro-capsules contain, as a filler material, a conductor and a polymerization initiator, a curing agent or a curing promotor. A wall member encapsulating the filler material is formed of a thermoplastic or thermosetting insulative resin. Therefore, if the micro-capsules in the anisotropic conductive material are broken or destroyed by pressure or both of pressure and heat, electrical connection can be established between electrode pads and electrode terminals of a wiring substrate through the conductors contained in the micro-capsules. Simultaneously, the polymerization initiator, the curing agent or the curing promotor flows out, so that the insulative bonding resin is solidified.
The above prior art typically achieves the anisotropic effect by controlling filler loading. In other words, to obtain an anisotropic interconnect the adhesive must use few particles. However, these prior art methods still have serious leakage problems if the filler loading is too high or too uneven. The filler loading is hard to control especially if the filler responds to gravity or magnetic fields.
In one preferred embodiment, the invention is an electrical interconnect comprising (a) at least one first electrical contact; (b) at least one second electrical contact; and, (c) an adhesive interposed between and in contact with the first electrical contact and the second electrical contact, the adhesive comprising an electrically non-conductive resin and particles, the particles comprising at least one electrically conductive material and a breakable coating of at least one electrically non-conductive material, wherein the first electrical contact is positioned close enough to the second electrical contact to break the breakable coating of the particles in the interposed adhesive such that the electrically conducting material of the particles is exposed and in contact with both the first electrical contact and the second electrical contact, wherein the exposed electrically conducting material has sharp edges. This embodiment includes semiconductor dies or chips and semiconductor packages comprising such an interconnect.
In another preferred embodiment, the invention is an electrical interconnect comprising: (a) a first substrate having a surface and at least one first electrical contact projecting from the first substrate surface; (b) a second substrate having a surface and at least one second electrical contact projecting from the second substrate surface and aligned with the first electrical contact, such that the first substrate surface is substantially parallel to the second substrate surface; and, (c) an adhesive interposed between and in contact with the first substrate surface and electrical contact and the second substrate surface and electrical contact, the adhesive comprising an electrically non-conductive resin and particles, the particles comprising a core of at least one electrically conductive material and a breakable coating of at least one electrically non-conductive material, wherein the first electrical contact is positioned close enough to the second electrical contact to break the breakable coating material of the particles in the adhesive interposed between the first electrical contact and the second electrical contact such that the electrically conducting material of the particles is exposed and in contact with both the first electrical contact and the second electrical contact, wherein the exposed electrically conducting material has sharp edges, provided that the coating of the particles interposed between the first substrate surface and the second substrate surface, but not interposed between the first electrical contact and the second electrical contact, is not broken. This embodiment includes semiconductor dies or chips and semiconductor packages comprising such an interconnect.
In another preferred embodiment, the invention is an electrical interconnect comprising: (a) at least one first electrical contact; (b) at least one second electrical contact; and, (c) an adhesive interposed between and in contact with the first electrical contact and the second electrical contact, the adhesive comprising an electrically non-conductive resin and particles, the particles comprising a core of at least one electrically conductive reactive material and a breakable coating of at least one electrically non-conductive material, the core comprising: (1) at least one first subparticle comprising a reactive resin, having conductive material therein, encapsulated inside a rupturable membrane; and, (2) at least one second subparticle comprising a catalyst encapsulated inside a rupturable membrane, wherein the first electrical contact is positioned close enough to the second electrical contact to break the breakable coating of the particles in the interposed adhesive such that the first subparticle membrane and the second subparticle membrane are ruptured, whereby the reactive resin and the catalyst react to form a conductive adhesive between the first electrical contact and the second electrical contact. This embodiment includes semiconductor dies or chips and semiconductor packages comprising such an interconnect.
In yet another preferred embodiment, the invention is an electrical interconnect comprising: (a) a first substrate having a surface and at least one first electrical contact projecting from the first substrate surface; (b) a second substrate having a surface and at least one second electrical contact projecting from the second substrate surface and aligned with the first electrical contact, such that the first substrate surface is substantially parallel to the second substrate surface; and, (c) an adhesive interposed between and in contact with the first electrical contact and the second electrical contact, the adhesive comprising an electrically non-conductive resin and particles, the particles comprising a core of at least one electrically conductive reactive material and a breakable coating of at least one electrically non-conductive material, the core comprising: (1) at least one first subparticle comprising a reactive resin, having conductive material therein, encapsulated inside a rupturable membrane; and, (2) at least one second subparticle comprising a catalyst encapsulated inside a rupturable membrane, wherein the first electrical contact is positioned close enough to the second electrical contact to break the breakable coating of the particles in the interposed adhesive such that the first subparticle membrane and the second subparticle membrane are ruptured, whereby the reactive resin and the catalyst react to form a conductive adhesive between the first electrical contact and the second electrical contact provided that the coating of the particles interposed between the first substrate surface and the second substrate surface, but not interposed between the first electrical contact and the second electrical contact, is not broken. This embodiment includes semiconductor dies or chips and semiconductor packages comprising such an interconnect.
In yet another preferred embodiment, the invention is an electrical interconnect comprising: (a) at least one first electrical contact; (b) at least one second electrical contact; and, (c) an adhesive interposed between and in contact with the first electrical contact and the second electrical contact, the adhesive comprising: (1) an electrically non-conductive resin; (2) multiple first particles, each first particle comprising a core comprising at least one reactive resin, having an electrically conductive material therein, and a breakable coating of at least one electrically non-conductive material; and (3) multiple second particles, each second particle comprising a core comprising a catalyst and a breakable coating of at least one electrically non-conductive material, wherein the first electrical contact is positioned close enough to the second electrical contact to break the breakable coatings of the first particles and the second particles in the interposed adhesive, whereby the reactive resin and the catalyst react to form a conductive adhesive between the first electrical contact and the second electrical contact. This embodiment includes semiconductor dies or chips and semiconductor packages comprising such an interconnect.
In another preferred embodiment, the invention is an electrical interconnect comprising: (a) a first substrate having a surface and at least one first electrical contact projecting from the first substrate surface; (b) a second substrate having a surface and at least one second electrical contact projecting from the second substrate surface and aligned with the first electrical contact, such that the first substrate surface is substantially parallel to the second substrate surface; and, (c) an adhesive interposed between and in contact with the first electrical contact and the second electrical contact, the adhesive comprising: (1) an electrically non-conductive resin; (2) multiple first particles, each first particle comprising a core comprising at least one reactive resin, having an electrically conductive material therein, and a breakable coating of at least one electrically non-conductive material; and (3) multiple second particles, each second particle comprising a core comprising a catalyst and a breakable coating of at least one electrically non-conductive material, wherein the first electrical contact is positioned close enough to the second electrical contact to break the breakable coatings of the first particles and the second particles in the interposed adhesive, whereby the reactive resin and the catalyst react to form a conductive adhesive between the first electrical contact and the second electrical contact, contact provided that the coating of the particles interposed between the first substrate surface and the second substrate surface, but not interposed between the first electrical contact and the second electrical contact, is not broken. This embodiment includes semiconductor dies or chips and semiconductor packages comprising such an interconnect.